This invention relates generally to electric power transmission and, more particularly, to guards for the protection of wildlife, such as squirrels, as well as protection of electrical power distribution and substation equipment.
While the apparatus of the present invention is particularly suitable for use with power distribution transformers installed on utility poles, those skilled in the art will recognize that it also has application to circuit breakers, capacitors, fuse cutouts, inductor insulators, underground cable terminators and other equipment commonly used in electrical power supply systems. Both wildlife and electrical power distribution and substation equipment are frequently destroyed when an animal simultaneously contacts grounded and electrically energized surfaces. In addition, a simultaneous contact usually results in a power outage that disrupts service to many customers. Customers are inconvenienced not only by the immediate lack of electric service but by the necessity for resetting clocks, videocassette recorders and the like. Electric utility companies also incur a significant expense as a result of such disruptive contacts. The expense may be for equipment, such as a transformer, as well as for the labor to stock, move and install replacement parts. Even if the replacement part is merely a fuse, the expense of dispatching trucks and personnel is still substantial.
The prior art includes various devices which have not been wholly satisfactory. They include an Electrostatic Animal Barrier for Electrical Equipment described in U.S. Pat. No. 5,648,641, issued to Guthrie on Jul. 15, 1997; an Insulating Shield described in U.S. Pat. No. 5,446,242, issued to Barrett on Aug. 29, 1995; and a Wildlife Guard described in U.S. Pat. No. 5,864,096, issued to Williams et al. on Jan. 26, 1999. The electrostatic apparatus of U.S. Pat. No. 5,648,641 utilizes projections in which an electrostatic charge is produced by current flow in the protected device. The electrostatic charge is relied on to discourage animals such as squirrels, from investigating and touching such apparatus. The other two noted devices are primarily rigid barrier devices.
Other prior art devices to which the invention relates have used a plastic enclosure in which two concave sections are hinged together. One section can be moved relative to the other to completely envelop a device such as a distribution transformer. At least some of the prior art devices have required service interruptions so the guard could be installed safely on the energized equipment. This is particularly a problem with unitary, one-piece structures. The installation of prior wildlife protective devices on distribution transformers may also be complicated by the close proximity of lightning arresting devices that may physically interfere with the installation of certain prior art devices.
An object of the invention is to provide new and improved protective apparatus that will more effectively and more humanely discourage animals from simultaneously contacting grounded and energized parts of electrical distribution apparatus.
Another object of the invention is to provide protective apparatus that can be installed safely on energized equipment in an efficient and cost effective manner.
Still another object of the invention is to provide protective apparatus for a power transformer that will not interfere with adjacent structures, for example, a lightning arrestor that is proximate to the power terminal of the distribution transformer.
It has now been found that these and other objects of the invention may be attained in a wildlife guard for live electrical power equipment to prevent wildlife from simultaneously contacting an electrically energized surface and an electrically grounded surface. The wildlife guide includes an arcuate member having a peripheral surface and a geometric axis that is perpendicular to the peripheral surface. An array of petals is carried on the arcuate member extending radially outward from the peripheral surface. Each of the petals is movable from a first position in which each of the petals is substantially coincident with a plane that is perpendicular to the geometric axis and extends through the member to a second position that is oblique to the plane.
In some forms of the wildlife guard apparatus, each of the petals is biased to a position that is substantially coincident with the plane. Each of the petals may be biased to a position that is substantially coincident with the plane by means of at least one spring. Various forms of springs may be employed. Each of the petals may also biased to a position that is substantially coincident with the plane by means of at least two springs.
In some embodiments, at least one arcuate shoe is dimensioned and configured for engagement with associated apparatus that is being protected. Other embodiments further include at least a second shoe dimensioned and configured for engagement with associated apparatus that is being protected. The first shoe and the second shoe may be disposed in opposed relationship.
The arcuate member may extend through an arc which is less than 360 degrees and have extremities that define a throat that is dimensioned and configured for passing around apparatus to be protected.
Each of the petals preferably have tapered generally planar surfaces and each of the petals carried on the arcuate ring may be disposed in closely spaced relationship to at least one other petal.